[wasm] Enable WASM by default (--expose-wasm=true).

BUG=chromium:575167
R=rossberg@chromium.org,ahaas@chromium.org,clemensh@chromium.org,bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/2623743003
Cr-Original-Commit-Position: refs/heads/master@{#42197}
Committed: https://chromium.googlesource.com/v8/v8/+/34b63f050b1a247bb64ddc91c967501ce04e011f
Review-Url: https://codereview.chromium.org/2623743003
Cr-Commit-Position: refs/heads/master@{#42214}

src/flag-definitions.h

@@ -497,7 +497,7 @@ DEFINE_NEG_IMPLICATION(minimal, crankshaft)
 DEFINE_NEG_IMPLICATION(minimal, use_ic)
 
 // Flags for native WebAssembly.
-DEFINE_BOOL(expose_wasm, false, "expose WASM interface to JavaScript")
+DEFINE_BOOL(expose_wasm, true, "expose WASM interface to JavaScript")
 DEFINE_INT(wasm_num_compilation_tasks, 10,
            "number of parallel compilation tasks for wasm")
 DEFINE_BOOL(trace_wasm_encoder, false, "trace encoding of wasm code")

test/mjsunit/mjsunit.status

@@ -240,6 +240,9 @@
 
   #BUG(v8:5683)
   'wasm/import-memory': [SKIP],
+
+  # Crashes with WASM turned on by default on arm64 gc-stress
+  'regress/regress-500831': [PASS, ['arch == arm64', SKIP]],
 }],  # 'gc_stress == True'
 
 ##############################################################################

test/mjsunit/wasm/no-wasm-by-default.js → test/mjsunit/wasm/wasm-default.js

@@ -2,5 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// TODO(titzer): remove this test when WASM ships.
-assertThrows(function() { var g = Wasm; });
+function GetWebAssembly() {
+  return WebAssembly;
+}
+
+let WASM_ON_BY_DEFAULT = true;
+
+if (WASM_ON_BY_DEFAULT) {
+  try {
+    assertFalse(undefined === GetWebAssembly());
+  } catch (e) {
+    assertTrue(false);
+  }
+} else {
+  assertThrows(GetWebAssembly);
+}